The change in QT dispersion on treadmill exercise test after coronary stenting / 대한내과학회지

ABSTRACT

BACKGROUND: QT dispersion (QTd) represents inhomogeneous ventricular repolarization. Increased QTd has been reported to be associated with ischemic heart disease and sudden cardiac death. Successful percutaneous coronary angioplasty (PTCA) produces a favorable recovery of inhomogenous repolarization and reduces QTd. Although treadmill exercise test is commonly used for follow-up test after PTCA, limited data are available about QTd during treadmill test. The purpose of this study was to evaluate the change in QTd and determine its clinical role in follow-up treadmill exercise test after coronary stenting. METHODS: 41 patients with significant coronary artery disease underwent successful coronary stenting, while 46 patients were medically treated. Treadmill exercise test was performed to compare QTd between two groups as a follow-up test at 6 months after coronary stenting and medical therapy. Treadmill exercise test was recorded in pre-test, peak exercise, and recovery 2 minutes phase. QTd and corrected QT dispersion (QTcd) were measured in these ECGs using a digitizer. RESULTS: Coronary stenting significantly reduced QTd and QTcd at 6 months after coronary stenting. QTd and QTcd did not show significant difference between coronary stenting and medical therapy group at initial EKG before treatment. After coronary stenting, QTd and QTcd were significantly reduced than those of medical therapy group. And the changes in QTd and QTcd were more marked at peak exercise (28.2+/-11.9 and 39.3+/-16.2 msec in coronary stenting group vs 40.4+/-20.5 and 57.8+/-30.0 msec in medical therapy group). Lesion location and diseased vessel number were not associated with changes in QTd and QTcd. CONCLUSION: Coronary stenting reduced QTd and QTcd significantly in follow-up treadmill exercise test. Coronary stenting appears to be more effective to relieve myocardial ischemia and to improve inhomogenous ventricular repolarization than medical therapy. The measurement of QTcd during treadmill exercise test may be a useful index to evaluate myocardial ischemia after coronary stenting. Clinical relevance of these finding will require further study.